Digital BW, The Print

I have been using recently this black ink to complement MIS hextone 
inks and using Paul Roark's curves on an Epson 1290 printer. I 
followed the advice of Jerry Olson here. The results are very good, 
very blak indeed, better than the MIS black I used before. Now I was 
going to buy a bottle to refill my cartridges and I read that this 
ink has 75% pigment ink and 25% dye ink. Is this something new, or I 
didnt notice? Would this affect longevity on prints? (Not that I 
aspire to see my prints in 100 years, but you know...) There is 
another set of inks (Generations Elite) with 100% of pigment. Is this 
as black as the other one? Is it something new?

Thanks in advance, especially to Jerry if he manages to read this.